Experimental investigation of input parameters on erosion rate and residual stress in core molding process

In the present study, in order to investigate the effect of impact angle and sand jet pressure on the erosion rate and residual stress in sand molding operation, the experiments are performed using gray cast iron, pearlitic ductile iron (PDI) and austempered ductile iron (ADI) as workpiece materials. To fulfill this objective, experimental tests are conducted in full factorial design with workpiece material, impact angle and jet pressure as input and erosive wear rate and residual stress as output parameters.According to the results, variation of impact angle of erosive particles intensively affects the erosion rate of materials in a way that, among the experiments which are carried out in lower impact angles (15 to 30°), ADI cast iron shows the maximum erosive strength however as the impact angle shifts to higher values (75 to 90°), PDI cast iron becomes more resistance against erosion. It can also be noted from the SEM images that in sand shooting process, the presence of flake graphite in gray cast iron causes more formed and grown cracks which significantly intensifies its erosion rate relative to ADI and PDI cast irons. Additionally, comparative analysis of results revealed that formation of surface micro cracks in gray cast iron material causes less induced compression residual stresses relative to ADI cast iron whose great stiffness leads to higher magnitudes of compression residual stress in sand molding operation.